The use of microwave ovens in the home has become increasingly popular in recent years because of its speed, economy, etc. Typically, home ovens have a power operating capacity of from about 400 watts to about 1000 watts, while institutional ovens have an operating capacity of from about 750 watts to about 2200 watts.
The popping of popcorn in a microwave oven has presented problems, typical of which is the low percentage of popcorn popped. Some of these problems were overcome by the invention disclosed in U.S. Pat. No. 3,973,045 to Brandberg et al. The package of the subject patent works very effectively and provides reasonably good popping results and overcame some problems attendant with popping popcorn in a microwave oven.
Another problem with popping popcorn in a microwave oven is that the oven, to achieve adequate popping, had to be a higher powered oven. It would be desirable to be able to achieve adequate popping in the lower powered ovens, i.e., for example, a 600 or 700 watt oven as opposed to 1000 watt oven.
It is well known that in the oven chamber of a microwave oven that there is a wide disparity of field strength--this is commonly referred to as hot spots and cold spots in the oven. What this ultimately results in is that one area of an oven will cook differently than another area of the same oven. Further, even with the same model oven, the hot and cold spot positions will vary between individual ovens. When initial work was done to improve popping performance of the popcorn, it was felt that the position of the popcorn within the oven was the parameter which caused either good popping performance or bad popping performance. One solution to this problem is disclosed in U.S. Pat. No. 3,835,280 to L. D. Gades, et al. Even though the structure disclosed therein was effective for improving popping performance, it was a relatively expensive solution to the problem.
Much effort has been devoted to improving the popping performance of popcorn in an oven, and these efforts have been directed primarily to changing the field in an oven cavity to eliminate cold spots. The problem was never considered to be a heat-loss problem since ovens used had adequate capacity for providing sufficient heat to achieve popping of the popcorn. Recent experimental work has unexpectedly indicated that the problem is not necessarily not and cold spots in the oven, but heat loss from the popcorn. The reason for not expecting heat loss to be the problem was that the floors of ovens were considered to be good thermal insulators. Test results indicate that this is not the case when popping of popcorn is to be achieved.
Thus, by providing a package for both the storage and popping of popcorn which would prevent heat loss to the floor of the oven, improved popping performance can be achieved. In fact, very unexpectedly, not only did the percent of popped kernels improve by use of the present invention, but also the volumetric expansion of each of the popped kernels improved providing a lighter, less dense popped popcorn.
Experimental data indicates that a decrease of 16% in the unpopped kernels can be achieved while an increase of about 17% in volumetric expansion can be achieved by use of the present invention.